1. Field of the Invention
This invention relates to synthetic oil-based, preferably polyol ester-based turbo oils which use a synergistic combination of phosphorous (P)-based and sulfur (S)-based load additive chemistries which allows the turbo oil formulation to impart high load-carrying capacity and also to meet or exceed US Navy MIL-L-23699 requirements including Oxidation and Corrosion Stability and Si seal compatibility.
Load additives protect metal surfaces of gears and bearings against uncontrollable wear and welding as moving parts are heavily loaded or subjected to high temperatures. Incorporating high load-carrying capacity into a premium quality turbo oil without adversely impacting other properties can significantly increase the service life and reliability of the turbine engines.
The mechanism by which load additives function entails an initial molecular adsorption on metal surfaces followed by a chemical reaction with the metal to form a sacrificial barrier exhibiting reduced friction between the rubbing metal surfaces. In the viewpoint of this action, the effectiveness as load-carrying agent is determined by the surface activity imparted by a polar functionality of a load additive and its chemical reactivity toward the metal; these features can lead to a severe corrosion if not controlled until extreme pressure conditions prevail. As a result, the most of effective load additives carry deleterious side effects on other key turbo oil performances: e.g., corrosion, increased deposit forming tendency and elastomer incompatibility.